The paper concerns an analysis regarding geometry of a grinding wheel used in grinding of cylindrical worm threads characterized by various geometry. It presents geometrical and physical factors having impact on the grinding process and a quality of grinding wheel. In particular, an attention is paid on the accuracy of grinding wheel’s outline if it is approximated by linear interpolation line segments which are obtained in the case of dressing on a CNC machine tool. On the basis of two grinding wheel outlines (Archimedes and circular-arched one), the relevance of the length of the segment line on the geometrical accuracy of wheel’s outline has been presented. In the case of development of a wheel dresser path on the CNC machine tool, the necessity of an customized approach has also been indicated.